Adult Bee Diseases

Unlike brood diseases, diseases of adult bees do not show themselves on the comb; the colony often weakens quietly. The path to a diagnosis is to read several clues in front of the hive and on the frames together, to measure the varroa level and, when necessary, to send a bee sample to a laboratory. This page introduces the group; the details of each disease are on its own page.

How to approach it

1. Look in front of the hive first. Are there crawling, trembling, flightless or dead bees? How many, at what time of day, in one hive or in all of them?
2. Then look closely at the bees. Wing shape, swollen abdomen, hairless shiny body, faecal staining.
3. Measure varroa. Most adult bee problems either start with or are aggravated by varroa and the viruses it carries.
4. Consider the surroundings. Is it in one hive or the whole apiary? If it started in all of them at the same time, poisoning comes to mind.
5. If you are not sure, send a sample. Nosema, amoeba disease and tracheal mites can only be told apart under the microscope.

Main diseases in the group

• Nosema (Nosema apis and Nosema ceranae; Vairimorpha in the new classification): A fungus-like parasite that damages the midgut. N. apis presents in spring with faecal staining, N. ceranae with weakening throughout the year without symptoms.
• Amoeba disease (Malpighamoeba mellificae): Settles in the Malpighian tubules; often occurs together with nosema and cannot be distinguished in the field.
• Deformed wing virus (DWV): Transmitted by varroa; bees with crumpled, short wings.
• Chronic bee paralysis (CBPV): Trembling, flightless bees with swollen abdomens, or hairless, shiny black bees; heaps of dead bees in front of the hive.
• Acute bee paralysis virus group (ABPV, KBV, IAPV): Rapid death of adult bees in colonies with high varroa levels; no specific sign in the field.
• Tracheal mite (Acarapis woodi): A microscopic mite living in the breathing tubes; weakening in winter. Details are in the Bee Mites section.
• Septicaemia: Bacteria multiplying in the haemolymph; rare and associated with damp conditions. Dead bees decompose quickly and the body segments come apart easily.
• Colony collapse: Bees disappearing without leaving dead bees behind; its own page contains a post-mortem guide.

From sign to likely cause

Samples for the laboratory

For most adult bee diseases a definitive diagnosis is made by microscopy or laboratory analysis. For nosema and amoeba disease, a sample of about 30 older (forager) bees collected at the entrance is usually requested; for viruses and poisoning the sample is frozen. Before sending the sample, ask the laboratory what number of bees and method of preservation it requires, and write down the hive number and the date.

Seasonal calendar

Common measures

• Keep varroa under control: it is the foundation of adult bee health.
• Renew comb regularly: spores and cysts accumulate in old, stained comb.
• Keep the hive dry: ventilation, a slight forward tilt, a sunny apiary site.
• Feed well: varied pollen, sufficient and suitable winter feed.
• Provide clean water.
• Do not buy colonies, queens or combs from unknown sources.
• Do not use antibiotics or unauthorised medicines on your own initiative: in many countries there is no authorised medicine for nosema and amoeba disease; such attempts leave residues and hide the problem.